Effect of Cryotherapy Modalities on Skin Temperature, Radial Artery Size and Flow Where Arterial Puncture Are Performed

Low-intervention clinical trial. The thermal and hemodynamic effects of different cryotherapy devices are evaluated. This study is included in the doctoral thesis of the principal investigator. Investigators: Principal Investigator: Julio Alberto Mateos Arroyo (RN, MSc, PhD student) Directors: Ignacio Zaragoza García (RN, PhD), Ismael Ortuño Soriano (RN, PhD), Paloma Posada Moreno (PhD). Setting: Faculty of Nursing, Physiotherapy and Podiatry of the Universidad Complutense de Madrid. The three interventions to be evaluated are: * Applying crushed ice. * Apply frozen peas. * Apply comparator. Hypothesis: There are differences in the reduction of temperature, dimensions of the internal lumen of the radial artery and blood flow inside it depending on the different modalities of cryotherapy (crushed ice or bag of frozen peas) applied in the anatomical area of the wrist, point of arterial puncture for blood gas analysis. Main objective: To analyze the effect of 3 cryotherapy devices on the radial artery area. Secondary objectives * To analyze the thermal behavior of the superficial tissue under study according to the cryotherapy device used. * To analyze the differences in the radial artery caliber before and after the application of cold in the different experimental modalities under study. * To analyze the differences in radial artery blood flow before and after the application of cold in the different experimental modalities under study. * To identify the safety pattern of the use of the different cryotherapy devices (adverse events). Design: Randomized controlled clinical trial. This is a crossover clinical trial in which all participants will receive all interventions and will be randomized in the order in which they receive them. Population: Adults with a good general state of health, who specifically do not have factors that could affect their thermoregulation or vascular pathologies. Main variables: * Skin surface temperature. * Radial artery size. *